The easiest way is asking for the Japanese father to recognize your child and he says he is willing.
If he is not willing, then you can come to us for help and we can send them a letter of a notification about recognizing the child. If they respond after this, then it is good.
If they do not respond, then we have to take harder steps to reach the goal of getting your child recognized. This will involve negotiation with the other party and sometimes even DNA testing.
We will take all possible ways in helping your child getting recognized, and do our best to help make your case successful. However, we need cooperation from you and information such as latest number and address of the father is necessary to start somewhere.
Once it has been proven that your child is indeed a child of Japanese, and father includes him in his Koseki Tohon, then we apply for his visa, so that he can obtain that status and live in Japan.
If Japanese father dies, it is almost difficult to be recognized. You must take action within 3 years after death.
Another small possibility is if you know you have family or siblings with your father, and they are willing to recognize you, then that is your last option. However, this kind of situation rarely happens.